A study of three patients with amyotrophic lateral sclerosis and a polyneuropathy resembling CIDP.

We report three patients with a syndrome that fulfilled clinical and laboratory criteria for definite chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) who failed immunosuppressive treatment and eventually developed progressive amyotrophic lateral sclerosis (ALS). Mean disease duration was 23 months (13-38) before death. Two patients had a family history of ALS without mutations of the SOD1 gene. Postmortem examination in one patient showed an endoneurial infiltration of mononuclear cells in lumbar roots and distal and proximal peripheral nerves, mainly around myelinated fibers, with demyelination and axonal loss, consistent with CIDP. The spinal cord revealed severe neuronal loss in the anterior horn, axonal loss in the corticospinal tract, and large numbers of phagocytes in the anterior and lateral tracts, indicative of ALS. Whether demyelinating polyneuropathy was coincident with ALS or was a cause or consequence of motor neuron degeneration in these patients remains to be elucidated. This unusual combination may provide an important clue in elucidating the pathogenesis of ALS in some patients.